Loss of visual acuity is a growing concern worldwide. The World Health Organization currently estimates to 2.5% the incidence of low vision in industrialized countries and this figure is expected to continue to increase with ageing population. Low vision may be generally referred to as a condition where ordinary eye glasses, lens implants or contact lenses are not sufficient for providing sharp sight. The largest growing segment of the low-vision population in developed countries is expected to be people aged 65 years old and older. This is mainly due to age-related eye diseases such as macular degeneration, glaucoma and diabetic retinopathy, cataract, detached retina, and retinitis pigmentosa. Some people are also born with low vision.
Low-vision individuals often find it difficult, if not impossible, to read small writing or to discern small objects without high levels of magnification. This limits their ability to lead an independent life because reading glasses and magnifying glass typically cannot provide sufficient magnification for them. In order to assist low-vision individuals in performing daily tasks, various magnification devices and systems are known in the art.
Among such devices and systems, desktop video magnifiers generally include a video monitor mounted on a stand having a gooseneck shape. A camera having a large optical zoom is installed on the stand over a working area on which a user disposes an object to be magnified, typically a document with textual content that the user wishes to read. The camera feeds a video processor with a video signal of a portion of the working area, and the video processor in turn feeds this video signal with an increased sharpness and enhanced contrast to the video monitor. The document is typically disposed on an XY translation table assembled on rails, allowing the user to freely move the XY table and the document thereon to bring different portions of the document within the field of view of the camera.
Conventional video magnifiers can be provided with optical character recognition (OCR) capabilities to allow low-vision individuals to access textual information. OCR generally refers to the operation of translating textual information contained in an image into machine-encoded text. Once extracted from the image, the machine-encoded text may be displayed to a user as suitably magnified text on a monitor, or be fed to and read aloud by a text-to-speech system, or be presented as Braille content. However, while appropriate for some uses and in some applications, OCR methods and systems employed in conventional video magnifiers have some drawbacks and limitations. For example, because the cameras employed in such video magnifiers generally have a relatively narrow field of view that can cover only a portion of a standard-paper-size document, OCR can only be performed on that portion of the document that is seen by the camera.
In view of the above considerations, there is therefore a need in the art for OCR methods and systems that can be used more easily and conveniently by low-vision individuals, while also alleviating at least some of the drawbacks of the prior art.